Epiphone Thunderbird Pro IV wiring.

Discussion in 'Pickups & Electronics [BG]' started by Grumpynuts, Nov 8, 2017.

  1. Grumpynuts


    Dec 6, 2016
    Ok, so here's the story. Playing, went to adjust my blend pot and all I got was a middle finger and dead bass. Opened her up, had two disconnected wires with a bit of shrink tubing on it, no signs they were ever connected and one that looked like it broke off. Took it to the repair shop thinking a quick solder job and I would be on my way. They were stumped. The main issue is that they felt it came stock with a push pull selector pot. While I didn't buy it brand new, the previous owner stated he had it stock, and judging by the apparently stock strings, I trusted him.

    Repair shop states they can get it soldered passively with the pot that was in there and it worked passively. And when they attached the push pull pot that they wanted to they got no sound. He also complained my tapewounds created a really soft sound, so I am wondering if there is any bias there.

    Any thoughts?
  2. Kikegg


    Mar 3, 2011
    Madrid, Spain
    Thunderbird Pro Wiring Diagram

    Anyway, those pickups can be used (they're passive) in a standard VVT or VVT-Switch schema. I did it long long time ago, later I sold the bass, and I remember the bass more usable in passive mode. Anyway in the URL above you have at least a pair or options. Greetings!
    Grumpynuts likes this.
  3. Bill Bohlen

    Bill Bohlen

    Mar 9, 2017
    Bumping this, I just picked up a 2009 Epi Thunderbird Pro IV secondhand. Love everything about it except the electronics. I, too, am getting an annoying buzz!! I can't find any loose wires in the control cavity, but the buzz gets a lot less if I put my hand on the input jack or turn the Treble all the way down. I've seen a lot of posts about this, but most end up with "I returned it and got a new one". Not an option for me. Although shielding the control cavity and pickup cavities may help suppress the noise, I don't think that's the real answer. Anyone get rid of this noise for good?
  4. Miles_ONeal

    Miles_ONeal Wrangler of Raucous Thunder Supporting Member

    Dec 1, 2017
    Round Rock, TX
    Did you get yours fixed? I just bought one, and the electronics and ground definitely need help. One of the controls doesn't seem to do anything, and this has more treble than bass. Should be an interesting project.
  5. Hi,
    I'm bumping this old lady since I would have chosen the exact same title for a new thread anyways. I want to remove the active preamp from my Epi Pro IV since
    I have looked up a lot of such schemes. Can anyone recommend a SPECIFIC passive wiring for those soapbars? Preferably VVT+3-way-PU-switch, or a good VVTT with not too much output/treble loss (Cadfael's guide has a Warwick and a very easy modern version of VVTT for instance). I have read through many threads on various basses and schemes and now I am confused as to which pots and caps to use for that soapbars and if VVTT really is so abhorrent as many folks say... VVT+tone cap selector would be good too, since I would keep PU switch in middle position anyways. Thank you very much. Anyone done such mods with an Epi Pro and can give definite answers?
  6. Excuse my double posting. Just in case anyone is interested and to share some thoughts on the wiring and performance of the T-Bird Pro IV (some old sources were never revised on that topic, which led to serious confusion on my behalf):

    - My Epi T-Bird Pro IV build around 2012 in Indonesia has passive humbuckers and an active tone control (some while ago even the Epiphone home page made unclear statements about this), just as mentioned earlier in this very thread
    - One loose red cable from the humbuckers is not to be connected to battery but rather to ground. However only IF it is really coming from the humbuckers. For BEWARE: My T-Bird had an extra red wire taped to both pickup cables which simply led from nowhere to nowhere! It was blank and unconnected on one side and insulated and hidden under tape on the other side. No function at all. Maybe those wires are the ones which caused all the confusion back then.
    - My T-Bird had an annoying howling sound which i notched out with EQ all the time plus when you boosted lows or highs the signal would instantly distort any effect or amp that would rather see a high impedance signal (no big surprise, I know). I found it too hot.
    - Thanks to Kikegg, I dared removing everything that was inside the cavity. My Bird has VVT wiring now with 500k pots and just sounds amazing. It is dead silent without any further shielding, no humming anymore, no howling sounds when playing A's anymore.
    - Given the punch and clarity the bass has now in passive mode even with old strings, I think my old active wiring was faulty/phasey/badly grounded from the factory all the years. The solder job of the original wiring looked unbelievably messy by the way.
    Miles_ONeal likes this.